The present invention relates generally to an automated washing system and method, and more specifically relates to such a system and method for washing semiconductor wafer cassettes and carriers.
Cassettes and carriers which are used to hold and transport silicon wafers for photolithographic processing become contaminated with resist flakes. Failure to clean these resist flakes from the cassettes and carriers results in these flakes being transferred to the wafers during subsequent processing operations. These transferred resist flakes are a major source of photolithographic defects, referred to as defects without inclusion.
Current systems available commercially are of two basic design types: hot deionized water and surfactant spray systems which are effective for normal particle removal, but which are not capable of removing resist flakes from cassettes; and solvent-based systems which are effective for both particle removal and resist removal. The first system mentioned above has the drawback of only removing particles. Removing resist flakes from contaminated parts is done by immersion and/or manual scrubbing with a resist removing solvent. The second system mentioned above has the disadvantage of the requirement for special handling and disposal of the resist removal solvents.